Photodynamic Therapy (PDT) has been hypothesized to be a new method for treatment of skin tumors like recurring basal cell carcinomas and has been demonstrated in clinical trial to be an alternative for controlling malignancies such as bladder, esophagus and lung cancers. The method depends on the selective retention of a photosensitizer by the tumor and its subsequent in situ activation by light of appropriate e wavelength and tissue penetration. The primary objective of this research proposal is to build and test a novel, low cost, non-laser, fiber optic red light source that has the potential to provide equivalent PDT bio-effects, but at much lower installation, maintenance and hardware cost and with greater safety compared to lasers. The goals of phase I are (1) to build and characterize a prototype, red light source with a fiber optic hand piece to illuminate uniformly skin areas (up to 1.5 cm in diameter) with 150 mW/cm2 of red light (630 plus/minus 15 nm) and (2) to test and quantify in an appropriate animal model its effectiveness for PDT in connection with the photosensitizing drug Photofin II. In phase II engineering prototypes would be developed and tested in a series of limited clinical studies.